PIPER PA46

Full Narrative

The pilot reported that he was performing the takeoff on a taxiway, due to a notice to airmen (NOTAM) in effect which closed the sole runway at the airport and allowed takeoff's and landing's from the parallel taxiway. During the takeoff roll, the pilot reported that the airplane hit a "dip" in the pavement and became airborne unintentionally. The pilot further reported that he heard the stall warning horn and pitched forward, but the airplane drifted off to the left into a ditch and the nose and main landing gear collapsed.

The left and right wings were substantially damaged.

The pilot did not report any mechanical malfunctions or failures with the airplane that would have precluded normal operation.

The airport manager provided video surveillance of the takeoff. The video showed that about 2,050 feet into the takeoff roll, the airplane pitched up, the nose and left main landing gear became airborne, but the airplane did not climb. Subsequently, the airplane touched back down and attempted to become airborne a second time about 300 feet further into the takeoff roll. The airplane's nose and main landing gear monetarily became airborne, but the airplane quickly touched back down and moved out of camera view.

The pilot reported that the takeoff weight was about 1 pound under the maximum allowable takeoff weight and he was attempting to perform a short field takeoff technique.

The density altitude about the time of departure was 3,168 feet, the pressure altitude was 579 feet, and the temperature was 93 Fahrenheit (34 Celsius). The Federal Aviation Administration (FAA) provides guidance on how density altitude affects aircraft performance. According to the FAA Koch Chart, the airplane would have likely experienced a 35% increase to the normal takeoff distance and a 25% decrease in a normal climb rate.

The FAA Airplane Flying Handbook in part states: "Due to the reduced drag in ground effect, the airplane may seem to be able to take off below the recommended airspeed. However, as the airplane rises out of ground effect with an insufficient airspeed, initial climb performance may prove to be marginal because of the increased drag. Under conditions of high-density altitude, high temperature, and/or maximum gross weight, the airplane may be able to become airborne at an insufficient airspeed, but unable to climb out of ground effect. Consequently, the airplane may not be able to clear obstructions, or may settle back on the runway."

It is likely that the pilot exceeded the critical angle of attack during the two initial climbs and the airplane did not exit ground effect due to insufficient airspeed at rotation.